… is from page 61 of the first volume (“Rules and Order,” 1973) of Hayek’s Law, Legislation, and Liberty:
The preservation of a free system is so difficult because it requires a constant rejection of measures which appear to be required to secure particular results, on no stronger grounds than that they conflict with a general rule, and frequently without our knowing what will be the costs of not observing the rule in the particular instance. A successful defence of freedom must therefore be dogmatic and make no concessions to expediency, even where it is not possible to show that, beside the known beneficial effects, some particular harmful result would also follow from its infringement. Freedom will prevail only if it is accepted as a general principle whose application to particular instances requires no justification. It is thus a misunderstanding to blame classical liberalism for having been too doctrinaire. Its defect was not that it adhered too stubbornly to principles, but rather that it lacked principles sufficiently definite to provide clear guidance….